Different profiles of chemokines, cytokines and cell growth factors in plasma samples from patients with leprosy, leprosy reactions and households contacts

Abstract

Background: Leprosy is a highly neglected disease that is considered a serious public health problem in many countries. This illness is characterised by a variety of clinical and histopathological manifestations that are related to the patient immune response.

Objectives: This work aimed evaluate the profile of circulating immune mediators in the plasma from patients classified clinically as paucibacillary (PB), multibacillary (MB), households contacts (HHC), type1 leprosy reaction (T1R), type2 leprosy reaction (T2R) and control individuals without medical history of leprosy (CTL).

Methods: To assessment of the plasma immune mediators was used multiplex microbeads immunoassay "Luminex".

Findings: The results showed that patients (PB) had a regulatory-biased profile, while MB revealed a pro-inflammatory trend of highly expressed biomarkers. HHC display conspicuously increased levels in the plasma of the chemokines (CCL2, CCL3, CCL4, CCL5 and CXCL8), pro-inflammatory cytokines (IFN-γ,TNF and IL-1β), modulating cytokines (IL-9 and IL-1Ra) and growth factors (PDGF, G-CSF and IL-2). Interestingly, HHC displayed superior production of IFN-γ as compared to other leprosy groups, indicating a putative protective role for this cytokine during chronic Mycobacterium leprae exposure.

Main conclusion: Further investigations are currently underway to elucidate the potential of these mediators as biomarkers applicable to the diagnosis/prognosis of leprosy and also T1R and T2R leprosy reactions.

Fig. 1:. plasma concentration of chemokines, pro-inflammatory/regulatory cytokines and growth factors in patients with paucibacillary (PB), multibacillary (MB) leprosy and household contacts (HHC). Plasma concentrations of chemokines, proinflammatory/regulatory cytokines and growth factors are shown in picograms per milliliter (pg/mL) in bar graphs highlighting the mean and standard error. The group of HHC living in endemic areas is represented by blue bar, the PB group by the orange bar and the MB group by the red bar. The gray background on each graph represents the 95% confidence interval (CI) of values observed in the plasma samples from the healthy control group living (CTL) in non-endemic areas. The significant differences (p < 0.05) for comparisons with the CTL are represented by the asterisk (*) and the significant differences (p < 0.05) for comparisons with HHC and PB groups are represented by the letter “a” and “b”, respectively.

Fig 2:. plasma concentration of chemokines, proinflammatory/regulatory cytokines, and growth factors in patients with paucibacillary (PB), multibacillary (MB) leprosy and leprosy reactions type 1 (T1R) and type 2 (T2R). Plasma concentrations of chemokines, proinflammatory/regulatory cytokines and growth factors rates are shown in picograms per milliliters (pg/mL) in bar graphs highlighting the mean and standard error. The PB group is represented by the orange bar, the MB group by the red bar, the T1R group by the light purple bar and the T2R group by the dark purple bar. The significant differences (p < 0.05) for comparisons with the PB, MB and T1R groups are represented by the letters “a”, “b” and “c”, respectively.

Fig. 3:. comparative analysis of ascending signatures of plasma biomarkers in patients with paucibacillary (PB), multibacillary (MB) leprosy, type 1 (T1R) and type 2 leprosy reactions (T2R) and households contacts (HHC). The panoramic profile of biomarkers (chemokines, pro-inflammatory/regulatory cytokines and growth factors) of each individual, in each group, is demonstrated by diagrams. The global median was the cut-off point for the segregation of individuals with low plasma concentration from biomarkers of individuals with high plasma concentration. The signature of plasma biomarkers in leprosy patients classified as PB group (orange circles), MB group (red circles), T1R group (light purple squares), T2R group (dark purple squares), healthy control groups (CTL): HHC living in endemic areas (blue circles) and CTL living in non-endemic areas (green squares) are presented as overlapping ascending signatures for comparative analysis of the profile of biomarkers between the study groups. The dotted line highlights the 50th percentile of the frequency of subjects with plasma concentration above the global median cut-off. The biomarkers presenting more than 50% of the subjects above the cut-off are highlighted by colour backgrounds, corresponding to each study group.

Fig. 4:. correlation networks between different plasma biomarkers in patients with paucibacillary (PB), multibacillary (MB) leprosy, type 1 (T1R) and type 2 leprosy reactions (T2R) and households contacts (HHC). Correlation networks of chemokines (blue circle), proinflammatory cytokines (red circle), regulatory cytokines (green circle) and growth factors (yellow circle) were assembled for each study group: healthy controls living (CTL) in non-endemic areas, HHC living in endemic areas, PB, MB, T1R) and T2R. The black lines show positive correlations between the biomarkers and the red dotted lines underscore the negative correlations.